The present invention relates to a trackball used for data entry into a computer system.
A keyboard is normally used to enter data manually into a computer system. These keyboards can be made in many different versions. However, they are all designed around the same basic concept: the keyboard contains groups of "Keys", each assigned to a specific letter or number, or one or more signs. Additionally, most modern keyboards for data systems also contain a series of function keys. Each function key may activate a special operation, depending upon the program being executed in the computer.
To simplify operations, many data systems and computer programs are also designed to work with a "Trackball" in addition to the keyboard. Although these trackballs may take many forms, their basic functions are the same: a unit containing a ball and one or more keys which may be pressed down. Two types of ball systems exist, as described hereafter.
In the first type, the ball is mounted on the bottom side of the trackball housing. Moving the trackball by rolling the trackball housing along a table will make the ball roll. This rolling ball operation is transferred to a corresponding movement of the cursor on the data screen of the connected computer. The ball operating can be translated into a distance and direction moved along an x-axis and a distance and direction moved along a y-axis. This movement is then transferred to the computer which moves the cursor on the screen in directions and distance corresponding to those given by the mouse movement. In most programs the relationship between a given rolling distance of the trackball ball and the corresponding movement of the cursor can be programmed, and also the acceleration of the trackball operation can be programmed.
The second type of trackball design differs, since the ball is on the top of the trackball housing. Again the trackball housing can be moved, but the basic operation is performed by having the trackball rest fairly permanently. The ball is moved by rolling it with the hand. This again will correspond to a movement of the cursor as described above.
Sometimes the term "mouse" is used instead of the term "trackball".
Both trackball designs therefore operate the cursor in the same way, the difference between the designs being related to the movement of the ball. Both versions typically have one or more keys 6, 7 as shown in FIG. 2, or 8, 9 as shown in FIG. 4, which the operator may activate in addition to the operation of the ball. Depending upon the computer program, the operation of the ball together with the pressing of one or more keys will create specified operations or reactions by the computer program.
Although trackball operations may increase an operator's efficiency, the trackball also poses some problems. Trackballs designed to be moved along a table (roller ball on bottom), may require a fairly substantial table area. In some computer areas, this may cause problems. Also, the operator has to move his or her arm away from the keyboard area, which may slow down the overall efficiency and create muscle problems.
The other trackball type with the roller ball on the top does not require a large additional table area for its operation. However, because the operator's hand shall control both the rolling of the ball and the keys directly, the design of the ball and the housing around the ball is very critical. As the human hand varies fairly much, this may cause some problems.
FIGS. 1 and 2 show at 10 a typical trackball design with a ball 11 on the under side of a trackball housing 12. For simplicity, this is referred to as "Type 1" in the following text. FIGS. 3 and 4 show a trackball 13 with a ball 14 on the top side of a housing 15. This will be referred to as "Type 2" in the following text.
When the ball on a trackball of type 2 is rolled by the hand of the operator, the ball movement is transferred to an "x-" and a "y-" control system internally in the trackball housing. Although this control system may vary in design, the basic principle is to register the movement of the ball on an x and y axis. Typically the ball 19 is touching three or four rollers, such as shown in FIG. 5 at 16, 17, and 18, where one or two are freerolling (such as 18) and the other two (such as 16 and 17) are connected to systems via measuring devices 20 or 21 for detecting the direction of the revolution of the roller and the length of rolling, as shown in FIG. 3. One of these detection rollers is referred to as the x-axis controller 16, the other one (90 degrees off the x-axis roller 16) is referred to as the y-axis controller 17. The free roller is shown at 18 (see FIG. 3). The two rollers 16 and 17 work independently. The direction and movement of the x- and y-controllers are transferred to the cursor on the data screen of the connected data system. Most programs permit the ratio between the movement of the ball in the x-direction and the y-direction, and the corresponding movement of the cursor in the same directions, to be set to suit the specific taste and requirements of the operator.
The type 1 trackball operates in the same way, except that the ball is on the bottom side and the ball is rolling by moving the trackball along the table.
The extra trackball keys such as 6, 7 or 8, 9 which may be pressed down by the operator are used to mark special cursor locations, start and stop of a cursor movement, etc. This will vary depending upon the program being run. Typically, a trackball may have two or three keys in addition to the ball. More than three keys are normally not practical.